The present invention relates in general to devices for dental practices, in particular to surgical drill templates used for drilling a jaw-bone for dental implant prostheses and to methods of manufacturing these drill templates.
The drilling of a jaw-bone (mandibular or maxillary) for implanting a dental prosthesis represents a delicate surgical intervention. Precision in performing the drilling of the bone according to a selected position, depth and orientation is of extraordinary importance for a satisfactory prosthetical result.
It is a consolidated practice to carry out the drilling by means of a custom-made surgical drill template which provides for the maintenance of predetermined parameters, such as geometrical location and depth of the hole and constant angle of the drilling axis. For this purpose the drill templates are provided with guiding holes having guiding tubes. Surgical drill templates have three basic designs: tooth-supported, mucosa-supported and bone-supported templates. Additionally, these drill templates can be further divided into types with and without depth control. A custom-made drill template is usually manufactured in a series of specific work steps.
Initially, the bone situation of a jaw is analyzed by means of imaging methods, such as x-ray, magnetic resonance (MR), computer tomography (CT) or digital volume tomography (DVT). The obtained images are used to determine how much bone is available in the region designated for implantation, what implant lengths are feasible, what augmentation methods might be necessary. Furthermore, it is also used to eliminate potential injuries of important nerves (e.g. N. alveolaris inferior, N. mentalis), blood vessels, tooth roots of neighbouring teeth or paranasal sinuses. The obtained planning data are transferred to a surgical drill template which is then manufactured according to techniques that are based for example on a plaster mould (cast), the use of CAD/CAM or rapid prototyping.
Nowadays, drill templates are utilized which are manufactured by CAD/CAM methods and in which the positioning and angulation of the guiding hole is determined with great accuracy on a computer in accordance with surgical, functional and aesthetic requirements.
Although these drill templates are made with great accuracy they still have several drawbacks which are not resolved by the state of the art. In fact, the manufacturing of the drill templates carried out by means of CAD/CAM methods is complicated and entails time consuming work steps, and is therefore expensive.
On the other hand, if the drill templates are manufactured by way of rapid prototyping, costly metal guiding tubes (guiding sleeves) must be used in the guiding holes. This is due to the fact that rapid prototyping is less precise as far as the manufacturing of the guiding holes is concerned. Moreover, the drill templates made by rapid prototyping can deform during the curing and/or drying process thereof which results in a loss of accuracy of the precise structures.
The precision of drill templates produced by rapid prototyping is thus highly affected by the properties of the employed materials.
Based on the problems outlined above, one objective of the present invention is to provide a drill template which can be manufactured in a simple and cost-effective way. It is another objective of the present invention to eliminate or circumvent the deformation of drill templates, for providing drill templates with an increased precision that will allow the exact positioning and drilling of holes for tooth implants, as well as an accurate implant bed preparation and insertion.
According to the invention these objectives are achieved by providing a drill template manufactured by mixed techniques of casting or rapid prototyping combined with drilling or milling and a method of manufacturing these drill templates as cited in claim 1 and claim 8, respectively.